Chapter 14 Water: A Limited Resource

Size: px
Start display at page:

Download "Chapter 14 Water: A Limited Resource"

Transcription

1 Chapter 14 Water: A Limited Resource

2 I. Importance of Water A. Cooking & washing B. Agriculture C. Manufacturing D. Mining E. Energy production F. Waste disposal G. There are more people and individual use of freshwater is increasing

3 II. Properties of Water A. Composed of 2 Hydrogen and 1 oxygen B. Exists as solid, liquid or gas C. High heat capacity D. Polar E. Forms Hydrogen bond between 2 water molecules H-bonds define water s physical properties

4 F. Water is never completely pure in nature G. Content of seawater (left) H. Many substances water dissolves cause water pollution

5 III.Hydrologic Cycle A. evapotranspiration evaporation transpiration B. condensation C. precipitation

6 IV. Distribution of Water A. Only 2.5% of water on earth is freshwater B. 2% is in the form of ice! C. Only ~0.5% of water on earth is available freshwater

7 V. Freshwater Terminology A. Surface water Precipitation that remains on the surface and does not seep into soil B. Runoff Movement of surface water to lakes, rivers, etc. C. Watershed (drainage basin) Land area that delivers water into a stream or river system D. Groundwater Freshwater under the earth s surface stored in aquifers E. Aquifer Underground caverns and porous layers of sand, gravel and rock in which groundwater is stored

8 Freshwater Aquifer

9 VI. Water Use and Resource Problems A. Fall into Three Categories 1. Too much water 2. Too little water 3. Poor quality/contamination

10 B. Too much water 1. Flooding Both natural and human-induced 2. Modern floods are highly destructive Humans have removed water-absorbing plant cover from soil Humans construct buildings on floodplains 3. Floodplain Area bordering a river channel that has the potential to flood

11 Urban vs. Pre-Urban Floodplains

12 Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods (next slide) Floodplain Government restrictions on building Levees can fail

13 Right: Suggested levee style, set back from river Left: Traditional levees adjacent to river

14 Floods of Summer 2008

15 C. Too little water 1. Typically found in arid land 2. Problems Drought Overdrawing water for irrigation purposes Aquifer depletion Subsidence Sinkholes

16 3. Saltwater Intrusion

17 VII. Water Problems In US and Canada A. US has a plentiful supply of freshwater B. Many areas have a severe shortages Geographical variations Seasonal variations

18 C. Water shortages in West and Southwest Water is diverted and transported via aqueducts

19 VIII. Water Problems in US and Canada- Surface Water A. Mono Lake (Eastern CA) Rivers and streams that once fed this lake are diverted to Los Angeles (275 mi away) Becoming highly saline Court ordered water diversion reduction B. Colorado River Basin Provides water for 27-million people Numerous dams for Hydropower (49) Colorado River no longer reaches ocean Colorado River Compact 1922 overestimated the amount of water available had to revisit this treaty in 2003 farmers agreed to sell some of their water they used the money to make their water systems more efficient

20 Colorado River bed in Mexico

21 Water Problems in US and Canada Aquifer Depletion Groundwater

22 IX. Water Problems in US and Canada Groundwater A. Ogallala Aquifer High Plains Largest groundwater deposit in world Water withdrawn for agriculture faster than nature replaces it

23 X. Global Water Problems A. Amount of freshwater on planet CAN meet human needs BUT, it is unevenly distributed and some places lack stable runoff B. Problems: Climate Change Drinking Water Population Growth Sharing Water Resources Among Countries

24 C. Water and Climate Change Climate change affects the type and distribution of precipitation Potential issues: Reduced snowfall will impact water resources downstream Sea level rise will cause saltwater intrusion into drinking water supplies

25 D. Drinking Water Problems Many developing countries have insufficient water to meet drinking and household needs E. Population Growth Increase in population means an increase in freshwater requirements Limits drinking water available Limits water available for agriculture (food)

26 F. Sharing Water Resources Among Countries Rhine River Basin (right) Countries upstream discharged pollutants into river Countries downstream had to pay to clean the water before they could drink it Aral Sea (next slide) Water diversion for irrigation has caused sea to become too saline

27 Aral Sea

28 G. Potentially Volatile International Water Situations Jordan River Nile River

29 XI. Water Management A. Main Goal: Provide sustainable supply of high-quality water Dams and Reservoirs Water Diversion Projects Desalinization

30 B. Dams and reservoirs 1. Benefits: Ensure year-round supply of water with regulated flow Generate electricity Provide recreational activities 2. Disadvantages Alter the ecosystem Reduce sediment load

31 3. Glen Canyon Dam Regulated flow has changed ecosystem

32 4. Salmon Population in Columbia R. very low due to dams that impede migration 5. Fish ladders help, but are not effective enough

33 C. Water Diversion Projects Water diverted to areas that are deficient Much of Southern CA receives its water supply from diverted water from Northern CA Controversial and expensive

34 D. Desalinization Removal of salt from ocean or brackish water Two methods: Distillation- salt water is evaporated, and water vapor is condensed into freshwater Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt Very expensive

35 XII. Water Conservation A. Reducing Agricultural Water Waste Agriculture is very inefficient with water Microirrigation - irrigation that conserves water by piping to crops through sealed systems - also called drip or trickle irrigation Laser technology is used to level land

36 B. Reducing Industrial Water Waste 5 industries chemical products, paper and pulp, petroleum and coal, primary metals, and food processing consume almost 90% of industrial water Stricter laws provide incentive to conserve water recapture, purify, and reuse water Water scarcity encourages further industrial recycling Potential to conserve water is huge

37 C. Reducing Municipal Water Waste Gray Water water that was alreadyused in sinks, showers, washing machines, and dishwaters Can be used to flush toilets, wash car or water lawn Water saving household fixtures Government incentives

38 D. Conserving at Home Install water-saving shower heads and faucets Install low-flush toilets Fix leaky fixtures Purchase high efficiency appliances Modify personal habits Use the dishwasher instead of washing by hand